Although there has been substantial effort in recent years to reduce or eliminate the risk of sunburn (erythema) produced by certain wavelengths in the ultraviolet (UV) region of the spectrum, there are still circumstances wherein skin becomes exposed to UV radiation. Such exposure may, in some cases, cause sunburn. Such sunburn may cause irritation and pain to the skin thereby leading to the need for having the sunburn treated.
A number of prior art formulations have been developed for the treatment of sunburned skin. However, such treatments have certain disadvantages. For example, sunburn treatments that provide a spray mist or a petroleum-based composition to the sunburned area do not produce a sufficiently large heat transference effect to remove heat from the sunburned area. Furthermore, petroleum-based compositions tend to produce a residue that needs to be subsequently cleansed from the tender and sensitive area of the sunburned skin. Such cleansing tends to cause further discomfort and irritation to the affected skin.
Preferably, a treatment for sunburn would satisfy several objectives simultaneously. The main objective for the treatment of sunburn would be to relieve pain, eliminate the source of heat, stop the burn progression, and, if necessary, help prevent infection. Thus, a useful treatment for sunburn preferably provides immediate relief from pain while also helping to promote healing. It would be desirable to have a formulation for treatment of sunburn to be combined in a reasonably convenient and cost-effective process wherein the prepared composition would remain stable during storage. Such a sunburn formulation should provide the relief and healing effects sought without producing an uncomfortable, sticky sensation and without soiling or sticking to one's clothing. In addition, the sunburn formulation should preferably not produce a residue that must be subsequently washed or removed from the sensitive sunburned area.
Since a sunburn is an inflammatory disorder, sunburn has been treated in the past with anti-inflammatory drugs. One of the most effective therapeutics is indomethacin [1-(p-chlorobenzoyl)-5-methoxy-2-methylindole-3-acetic acid], a non-steroid chemical compound that has been widely recognized for its outstanding anti-inflammatory, anti-pyretic, and analgesic properties. However, indomethacin can become unstable when mixed with certain carriers for topical applications, and therefore, oral administration is sometimes the preferred method of administration.
Oral administration of indomethacin has previously been reported as effective in relieving pain, reducing fever, and providing increased mobility in patients with inflammatory disorders, including those of a rheumatic nature. When orally administered, the drug behaves as a systemic medicine that passes into the bloodstream for general distribution in the body. As in the case with numerous other drugs, not every one can satisfactorily accept this drug by the oral mode of administration, particularly over extending periods of therapy. In addition, oral administration does not provide for the direct and concentrated application of indomethacin on an affected area, such as an area of sunburned skin.
Similar deficiencies also exist in the treatment of skin burns as a result of radiation therapy. Past treatments have utilized moisturizing creams or ointments to soothe the skin burns, however, such creams and ointments do not contain active anti-inflammatory or anesthetic agents to reduce pain or itching. Topical hydrocortisone creams or ointments have been utilized to reduce inflammation and discomfort, but such treatments typically provide only temporary relief for up to 1-1½ hours. Topical anesthetic creams or ointments work to reduce pain, but similarly, only provide for the temporary relief of such pain. Other creams, such as silver sulfadiazine cream 1% (sold as Silvadene Cream®), are used to treat radiation burns having blistered areas and ulcerations in order to reduce the pain and incidence of secondary skin infection, however, such creams' effects are limited when applied to first degree burns.
It would be desirable to provide a non-oral method of administering indomethacin for the treatment of sunburned skin. In addition, it would be desirable to provide a carrier vehicle for the topical application of indomethacin whereby local treatment of inflammation is achieved to an area of sunburned skin. It would also be desirable to provide a carrier for indomethacin that provided a topical application which utilized a reasonably convenient and cost-effective process that remained stable during storage. It would be desirable to provide a non-oral method of administering indomethacin for the treatment of mild to moderate skin burns caused by radiation therapy or excessive heat.